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7 Posts
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1392
July 8th, 2013 17:00
VMAX 10k balancing
As we are all aware one of the most important aspects of running a VMAX is balance.
Long story short we have a VMAX that is very unbalanced between BE processors for the SATA tier.
With the v1 hardware and 4 engines, 8 directors, there is a total of 32 BE processors. The first 3 engines have between 9 and 14 drives per BE processor, engine 4 has 2 drives per BE processor, and is cold most of the time.
How hard would it be to drain some of the disks from the first 3 engines and physically move them to engine 4 and add them back into the disk group And rebalance across them.
Let me know if this makes sense.
-sean
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AranH1
2.2K Posts
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July 9th, 2013 11:00
The drive removal from one slot and the insertion into another slot will require BIN loads on the array, and will most likely require two BIN loads: one to remove the drives from the Disk Group (drive deletion in the bin) and one to add the drives to the Disk Group.
Those operations will handle the necessary details you are concerned about. The drive deletion from the bin requies the full config lock during the CCA review, but the drive addition can use the no-lock bin load process for hardware only upgrades.
binarybob2
1 Message
1
July 8th, 2013 21:00
Hi Sean, we are planning on doing what you have described. It only differs in that we are moving disks from a vmax-10k to a vmax20k. The disks originally were in the 20K behind old engines. We now have 2 new engines and I ran it past EMC to get the disks moved to the newer engines. They said no problem. So our procedure will be:
1. Drain disks on VMAX-10k
2. Move disk to VMAX-20K.
3. Add disks to pool.
I don't see any reason why it can't be done on a single array. Only caveat would be to watch your performance during the moves.
Regards
Geoff
Vipin VK
2 Intern
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812 Posts
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July 9th, 2013 01:00
Consider moving this discussion to Symmetrix Support Forum (Actions > Move)
s24sean
7 Posts
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July 9th, 2013 06:00
Agreed, and thank you for all the responses.
The SATA tier is currently the most unbalanced and where we have the most space currently. No silver bullet, but should hopefully help a bit.
Now correct me if I am mistaken. We should be able to just drain the individual disks without worrying about the RAID 6 set it is part of, because the hyper's are really where the RAID happens and would move these with the drain process.
-sean
Quincy561
1.3K Posts
1
July 9th, 2013 06:00
It is possible, however SATA drives shouldn't be doing more than 50 IOPs per disk, so it takes a lot of them to create imbalance, but they generally are RAID6 which does put more load on the CPUs.
Quincy561
1.3K Posts
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July 9th, 2013 07:00
Correct, if you drain all the logicals on a physical disk, then it can be moved someplace else in the system.
s24sean
7 Posts
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July 9th, 2013 10:00
One more question.
Is there anything else for the drive that the VMAX would store, for example, does it store the drive serial number and if a drive gets plugged into a different tray that it wouldnt be happy.
Let me know if this makes sense
Sean
AranH1
2.2K Posts
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July 9th, 2013 11:00
Yes, if you have the capacity overhead in that pool drain as many disks as possible while still being able to service the IO and capacity requirements from that pool. This way you are limiting the number of times you have to change the bin, which is not a technical issue but as you probably know adds considerable time to the change process.
s24sean
7 Posts
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July 9th, 2013 11:00
Excellent again thank you!
So we would want to queue up a lot of drives, and limit the number of BIN changes.